I agree, reducing it to "willpower" is roughly the same thing as reducing it to "calories in, calories out". Neither one actually helps you achieve it. And saying it's only "willpower" and nothing more is possibly more misleading, and more shaming than the caloric equation.
I found out personally that focusing on willpower doesn't work very well, thinking that way makes it easier to fail mentally. You're trying to focus everything you have on not eating food, and judging your strength by whether you succeed. It's like the psych test of trying not to think of a polar bear. (http://www.apa.org/monitor/2011/10/unwanted-thoughts.aspx) Trying not to think about something is harder than thinking about something, and doubly harder than the habits we don't think about. Focusing on willpower is setting up such a monumental task that almost nobody can achieve, and the very few people that do have mentally trained for it.
It does take me the right mental frame of mind to stick to a reduced calorie diet, but I don't consider it willpower, it's more of a way of thinking and arranging my life so that I don't need willpower. It's almost opposite of willpower. I think about what I should do and how I should feel, instead of what I shouldn't, and I form new habits so that I don't have to think about it all the time or use the power of my will to overcome my tendencies.
I'm not sure but I feel like women generally have it harder when it comes to calorie reduction. My wife has to eat under 1500 to lose weight as well, and she's active and doesn't have bum knees or thyroid problems. Either way, that stinks for you mom. Does she regret her previous sport life at all now, or does she have fond memories?
